Turn It Off
by LaniRamen
Summary: Lots of people think that Sherlock needs help. No one thinks that Katherine needs help. But after she helps our favourite duo solve a few cases, they realise Katherine is a mystery that needs solving - and in the process, can she solve Sherlock? Eventual Sherlock X OC
1. Chapter One - Beginning

**Disclaimer: **I do not own any of Sherlock, all rights go to the BBC and any other respective owners that there might be. All I own is Katherine and other OC's that may pop up occasionally. These are mine and I hope you do not take them, unless you ask. Everything still goes to respective owners and stuff.

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It was on a chilly Friday morning that Katherine met the two strange men. She had just gotten into work, and was drinking an early-November pumpkin spice latte, checking what new things were coming into the Victoria and Albert museum. A comfortable silence covered her office, much like her beloved red turtleneck that snuggled up to her body and kept her warm. Only on occasions such as this (cold Casual Fridays) did she wear it; despite many employees of the museum wearing semi-casual clothes everyday, she did not succumb to late-autumn laziness and wear casual every day, only on the proper Fridays.

The memos on her desk suggested a new collection of dresses coming in. They were for the new exhibition, one of the paid ones, about fashion in the early nineteenth century. But the notes also told of the last-before-last exhibition's transfer to a museum in Germany. It contained a selection of hand-crafted decorative guns; some of them had been used before, and some had not, but they were all beautiful. From rifles to shotguns to handguns, the variety was enormous. And hugely interesting.

This (when she had almost finished reading the second memo) was about when two men entered her office without knocking or calling or having any sort of announcement that they would be coming in to meet her. Surprised, to say the least, she greeted them with a quiet 'hello', slightly warped by her mostly Irish accent.

One of them was short and blonde, with eyes the colour of tree bark. He was obviously annoyed at the other man, and from his face, was about to tell him off like he was a child, despite the height difference.

The second man was tall, with blank silvery-blue eyes and curly, dark brown hair that only served to enhance the colour of his irises. A long black coat and a blue scarf provided cover from the chill. As he looked down at her, she felt an overwhelming air of superiority emanating from him, but she had to stay and try not to be submissive. Do as the museum's curator told her and be straightforward with people.

"Um, hello."

She was not good at being straightforward.

"We are looking for a short-range gun, with small lead barrels as ammunition, and I understand you currently have an exhibition of antique guns in the warehouse," the tall man said. The shorter man glared at him in a way that said 'you complete dickhead'.

"Please," she heard him whisper furiously at the tall man, who gritted his teeth and followed the command.

"Please."

"Um, we have a 1760 espingole blunderbuss, I think." Her voice was barely over a whisper. A soft snort could be heard from the taller man, probably because of her shy nature. "I could show it to you if you'd like."

"That would be lovely. Thank you," said the shorter man, as she led them towards the storage area. "I'm sorry for his behaviour, he's just so..."

"Brilliant? Do try to quieten your whispering, John, you're giving yourself away." She laughed quietly so as to not give away her amusement to either man.

"I'm John Watson, by the way. That is Sherlock Holmes."

"Katherine Beaulieu." Her hand found a brass doorknob and she opened it to reveal a large storehouse for previous exhibitions that had not moved on yet, filled with antiquities from every age and place. Clothes, guns, swords, furniture, virtually everything imaginable was inside the huge room. John gasped, Sherlock seemed unimpressed, and Katherine's lips turned to a slight smile at all the history stored right where she worked.

She led them to the guns exhibition section. While she was trying to find it her mouth moved as if reciting the code for the gun, her fingers flicking quickly in the air like she had memorised the positions of each item; actually, she had. Her memory led them to a long, thin brown box with a padlock on the outside that matched the locks on all the other cases around them. The password, Sherlock noted, was 965.

Inside was a gun. To be specific, "A 1760 espingole blunderbuss. This is the only one in this exhibition that meets your criteria." Sherlock nodded, then lifted the gun and examined it.

"What do you notice?" The question was directed at John. Katherine, however, seemed surprised at some aspect of the weapon.

"It's been shot-"

"There's a smudge on the brass!" Katherine hissed, interrupting John. She was about to polish it with her sleeve (improper but alright cleaning is better than a smudge), but Sherlock stopped her and inspected it. He then flipped the gun over and inspected the other side for fingerprints. "And the barrel is unclean. Someone's used this recently. I assume this is for some sort of police investigation, yes?"

"Yeah," John supplied, while Sherlock just rolled his eyes.

"Who has access to the codes?"

"Only me and the other people who unload. Oh, and the curator, of course. He hasn't been here for a few days without excuse. His name is Gerry Thomas." John seemed surprised. Sherlock's face... Well, it barely showed, but it was slight approval. He placed the blunderbuss back in the case and locked it back up, changing the code back to a default 000, then nodded again.

"Thank you for your help. We may need it again, so don't think you've seen the last of us," he said with a slightly cheeky smile. Then, with a swish of his coat, he turned and guided himself out of the storage area. John followed after a multitude of apologies and gratitudes.

It had been a strange but good day.

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_**Um, hello, internet! I realise that this is a very short chapter, I do, but it's just basically like a prologue for the rest of the story. Sorry if the little length is annoying. But it's just a tester to see how everything is and how many people are interested and things. Mm, this note is a bit long.**_

_**Anyway, I hope you all have a lovely day and night and whatnot. Thanks for reading, favourite, review, do whatever, and be happy! Season Three's almost here!**_

_**~Lani**_


	2. Chapter Two - Petals

**If you really feel the need to look at a disclaimer, and have, for some reason, decided to start my story on the second chapter, please consult the top of Chapter One - Beginning.**

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It was about two weeks later when Katherine saw one of the men again. Now mid-November, after a small amount of snow, frost, and all things chilly, she was not at work. Well, she was; but volunteer work at a public library nearby. On every Saturday for the past two years she went and volunteered. Most of the people she worked with knew that, which eventually led to her seeing one of the sort-of-police again. The books that had been returned the previous day needed to be put back on the shelves. So, as she was generally the first person to get into the library in the morning, she was tasked (voluntarily) to put the returns back where they were meant to go.

She placed a Nancy Springer book back onto its shelf, then heard the sound of the door. Her mouth opened as she was about to reprimand the too-early bird; but it closed when she saw who it was.

"Mr. Holmes," she greeted quietly. He shook his head gently and his curls bounced.

"Sherlock."

"What?"

"Call me Sherlock. Mr. Holmes is my brother, Mycroft, who you will undoubtedly have the misfortune to meet at some point."

"Oh," she mumbled.

"I did go to see you at the Victoria and Albert, but one of your colleagues informed me - rather rudely - that you do not work on weekends and that I should not barge into other people's offices without permission. Volunteering at a library, by the way, a good idea for one with such a good memory."

"It's hyperthymesitic," she said, still talking as if speaking was illegal and she was breaking said law.

"That would explain it. Though I wonder how, out of the six officially reported cases, you managed to get it. Now, coming to the point," he said while striding over to her, done with his overlooking of the library that she assumed would be committed to memory now; he was, after all, an obvious genius. "I require you to investigate a coat of arms from a crime scene that I cannot recognise." He handed her an A4 piece of card. The picture was blurry, but the obvious colours were yellow, blue and red. Another of the librarians walked in the door right at that moment; it gave her the opportunity to see the normal symbol if it had not been cleaned away already.

"I can't see it properly. The real one would be able to be identified more easily, so I think you should take me to wherever it is you found this," she suggested. Then, to the other librarian, "Hey, Cindy, I sort of need to go out for a little while. I'll be back though. The returns are all on the shelves." At Cindy's approval, she grabbed her black winter coat (the second layer of protection; she had her red turtleneck on) and led Sherlock out of the building.

"You might faint from the blood, there's quite a bit at this one." He smirked and hailed a cab, seemingly as if he was cab-royalty, then got in and gave a destination to the driver after Katherine followed.

"Right. Of course," she said, beginning to mumble again, after the initial excitement wore off. "I can tolerate blood." Finally, not only something interesting to spice up her extremely mediocre life but also something to do with her favourite false discipline: symbology. Robert Langdon, a character from multiple Dan Brown thriller novels, was a professor of religious iconology and symbology, and this partially led to Katherine's love for ancient symbols that edited or influenced history in any way, shape or form.

Sherlock swiftly exited the vehicle after paying the cabbie. She followed him into a cute little two-storey house with a nice garden and painted a light cream colour whose homey demeanor was completely and utterly destroyed by the yellow police tape surrounding the area. After he passed through, Sherlock held said tape up for his new assistant, ignoring the weird look a few of the police outside the house were giving him. Two policemen guarding an entrance let both of the newcomers in.

"Ah, Sherlock. Come with an answer to our coat of arms mystery, then?" A man said in a form of greeting. Then he looked at Katherine, who shrunk inwardly, like a dying star in slow motion. "Who's this?"

"A colleague," he said, brushing past the other man and heading towards wherever the symbol was.

"Blimey. Oi, since when have you had so many friends?" The man asked before offering his hand. "I'm Detective Inspector Lestrade."

"Um, Katherine Beaulieu." They walked in the direction Sherlock had disappeared to moments ago, and she mentally prepared herself for whatever might lay ahead in the room upstairs.

"So who are you? Last time he brought someone to a crime scene was about three years ago, and that person ended up being his old flat mate and best friend. I assume you aren't his girlfriend," he chuckled, causing her face to go a light shade of pink.

"No. I've only met him once before today. He came to the museum I work in and asked about a kind of gun in one of our exhibitions. Our curator was arrested."

"Oh, so you're the girl from the V&A. John told me about you. Said you made quite an impression on ol' Sherly."

"Didn't seem like it."

"Never does, really; some of us at the Yard are betting on whether or not he's got Asperger's." They rounded the corner to find the man himself standing impatiently by the entrance to a bedroom with a wall with a large, crudely drawn coat of arms on it. Katherine's eyes immediately widened and she stared for a second. It took her a little while to realize there was a trail of blood leading from the hallway, just after where Sherlock was standing, leading to the bathroom. Quickly, she clenched her left hand into a fist and then relaxed it. Hopefully Sherlock had not noticed. Carefully, as to avoid the blood line, she walked into the room and began to examine the symbol.

"It's the coat of arms for Denmark," she noted aloud. "But there are more søblade than normal, which probably means that either our painter didn't know the correct number or they knew it was only fixed in 1819, so this could be a version from before then. The crown is also different; this is the crown of Christian the Fourth, not Christian the Fifth as it is meant to be." Unknowingly, she had just solved the case with her expertise in history. But, as she did not know this, she continued to inspect the messy painting, taking note of the specific colours and paints and brushstrokes used, trying to glean more information on the murderer.

"Our suspect Mr. Laufeyson is the culprit. You can go arrest him now," Sherlock said dismissively, the added hand wave just enhancing the laziness of the gesture. Surprised, Katherine turned around.

"What?"

"We have a suspect who likes fourth kings," John said casually, entering the room from around the corner. Dismissed with an 'oh', she returned to the wall. Her fingers brushed against one of the søblade lightly. Noticing a slight red stain left from the paint, she touched it to her tongue. Blood. The søblade, or flower petals, were correctly shaped like love-hearts; but there were extremely thin strips of yellow going through the middle of each red shape; they looked more like flower petals that way.

"No, you're wrong," she said quietly. "It is not whoever you're going to arrest, look; there are more of the søblade, or hearts, than there should be and they look too much like proper flower petals to be in the Denmark coat of arms. You have the wrong man."

"Ah, yes!" Sherlock rushed over and touched the yellow strip in one of the petals. "Of course. It's his wife! Framing him with the fourth kings, but she just could not resist the urge to make it pretty. Obviously." John's eyebrows shot straight up. His flatmate, the consulting detective, possibly the most narcissistic man on Earth - letting someone, let alone a woman he had met just once before, prove him wrong and not dismiss it? Had something supremely important happened between them? But he could tell that nothing had, and it was just that his companion was trying his very best to keep this woman in his atmosphere; her historical knowledge could be useful later on in cases, and, supposedly, some aspects of her were mysteries. The detective had also gotten better at being human after... well, the Fall. Lestrade was about to point this out when John shook his head, a slight gesture that Sherlock did not notice, telling him to not mention it. Instead he devised a plan to get both main solvers of the case in a social (instead of working) meeting. So he walked to Katherine and asked her a question;

"Would you like to come to our party later?" This statement severely irritated Sherlock, and surprised Katherine. She had not been invited to a party in over three years; he had not heard of this gathering, and, because John was his _friend_, he would most likely be invited to the party (which he would not be able to decline) leaving him much less space to think. How annoying.

"We are not having a _party_, John."

"Yes we are."

"No."

"Mmmhmm." A confused expression changed Katherine's face into one with crinkled eyebrows and a slight frown, paired with her head tilted to the side by about an inch. "We've been on this case for a while, figured we might as well have a little party celebrating the arrest," the blogger explained.

"Oh, okay, that sounds nice. I might come. When is it?"

"How about seven?"

"Yes, I'll come. That sounds lovely." Sherlock had a scowl/frown on. John was being pesky. He could have a party whenever he wanted, but while he needed to solve a new puzzle (whose name happened to be Katherine Beaulieu) he need silence; social gatherings are not the place for that at all. But the puzzle (still Katherine) would be there, so... Perhaps it could be of some use.

"Yes, yes, the address is 221B Baker Street. The door will be open, just wall up the first flight of stairs, we will be there. Now, come on John! We have a party to plan!" John said something about Lestrade being invited as well before he was dragged out the door by Sherlock. Everyone left in the room was dumbfounded at the sudden and seemingly unprovoked change in idea, wondering what the hell had happened to the mopey and unsociable man from a minute ago. Oh well.

Katherine said her goodbyes - which was pretty much just to Lestrade - and left. Police sirens wailed as the order for arrest was being carried out, having just been fully processed. Hopefully the reason for the culprit's murder was something relatively normal; perhaps drugs, or some kind of mental disease, and hopefully not for fun. So many hopes. Katherine ignored the strange thoughts at the back of her mind tugging her towards something she did not want to do, and instead walked down the road to get to a busier road to catch a cab that could take her back to the library. She did, after all, still have to relieve Cindy.

A black car pulled up beside her.

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_**Hello again! I'm pretty happy with the response I've gotten so far, 53 views in four days! And 5 follows! And 2 favourites and 2 reviews! I'm such a newbie, aren't I? Anyway, I thought I'd post this one a bit early because of the good stuff I'm getting from this. So yay for you! A bit longer than last time as well.**_

_**Thanks to reviewers; rycbar15 and scarlet tribe.**_

_**Have a nice day/night/whatever!**_

_**~Lani**_

_**EDIT: I'm so sorry for the wait, guys, I guess I've taken a holiday break. But I've just edited this chapter to fit in with season 3 and I'm planning on posting another chapter tonight if I finish writing it. Then I shall post another next week! (I'll try and pre-write a few chapters to avoid new waits as well.) **_

_**~Lani**_


	3. Chapter 3 - Standing

_**Updated second chapter to fit in with season 3; check after Katherine realises the søblade are flower petals.**_

_**Disclaimer is one chapter one.**_

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Of course, she had no idea whatsoever that this car was for her. There was no reason for her to think so; never, in her whole life, had she been kidnapped, or had a fancy, black car pull up to her with no warning. With a valid reason, yes. Many had. But not... Without one. So, unknowingly ignoring one of the most important men in Britain, and possibly the whole world, she continued to wind her way to the main road to find a cab. It took her a little while to realise that the sleek machine next to her was inching along at her side. When she did, she rolled her eyes and knocked on the glass, expecting a different person than the woman who opened the door and stepped out, showing that it was for her. Katherine's eyebrows creased.

"Who are you?"

"Uh, Prudence."

"That's not your real name, is it," Katherine dead-panned, her question coming out more like a sentence.

"Nope. Can we go now?" Impatient, impatient. But Katherine did climb into the backseat of the car, wise enough to shut up when 'Prudence' gracefully manoeuvred herself in afterwards - much better than Katherine's awkward shuffling - even though she had questions like who her boss was and why they were going wherever they were going. Not much point asking where. Probably somewhere remote... Like the old, disused, dilapidated warehouse the car pulled up to. How predictable. It almost made Katherine disappointed; but whatever feelings she had were being very slowly an carefully taken over by the fear that this person was possibly someone she thought was dead.

She knew she was wrong when she spotted the umbrella.

"Hello, Miss Beaulieu. Please, take a seat; your old wound must still ache, hmm?" The man with the posh accent tapped the chair in front of him with the tip of the twirled umbrella.

"I've never had a serious injury in either of my legs. Whatever or whoever your source is, legal or illegal, they've got it wrong." Inside herself, she smirked. She had said it in a sassier tone than expected. It probably would have surprise most people she knew who hadn't seen her when she was scared. He defence mechanism was sass; a dangerous fire to play with, it could either protect you or burn you to a crisp.

Her inner smirk disappeared, however, when the man spoke again.

"I never said it was in the legs," he said ominously. "Now, sit."

"No. I'll stay standing." Uncomfortableness began to make her fidget slightly under the piercing gaze the man flicked over her, all of her, perhaps her very soul if she believed in such a thing. Reminiscent of something else she had seen not long ago...

"Sherlock does seem to pick such stubborn friends, wouldn't you say? John in fact said the same thing when I told him to-"

"Oh!" Katherine mentally face palmed for not having figured it out a moment ago. It was so incredibly obvious. They shared expressions, the same bored look upon their faces, and despite looking very little like each other, their eyes were almost exact replicates of each others'. "You and Sherlock are brothers, aren't you? He said earlier that I'd meet you. Mycroft, I think."

The smirk falling off his face was her reward.

"Yes. Though not many people realise it quite that quickly. I can see why brother dear likes you, with your-" he paused to flick through a notebook, then continued "-hypothalamic memory and above average deduction skills. What are your intentions with my brother?"

Despite the cold way the elder Holmes said it, the fact he had kidnapped her showed just how much he cared for his sibling, and so Katherine thought it best to be helpful. "You'd probably be better off asking his intentions of me. I've never actually met him when he isn't on a case, and he only ever asks for my help when on one involving history and symbols. Although, John did ask if I wanted to go to a party, which Sherlock then dismissed as nonexistent, but then changed his mind and apparently decided to have it at his flat."

"You've never been there; how do you know it's a flat?"

"221 B. How many houses, in London, have B's on them?"

"Perhaps he lives in a hotel."

"No hotel rooms have B's unless it's really bad quality, and by the state of Sherlock's cleanliness, I'd say he does not live in a hotel. Plus why would he, when he's got all that spare money? He could go live almost wherever he wanted." Mycroft emitted a humming sound, which Katherine took to be agreement. He opened, then closed, then opened his mouth, much like a goldfish. This woman had higher observational skills than almost everyone - though not over any of the Holmes family, except their parents. So Mycroft changed his plans.

"Despite my original intentions, I've decided to leave you be. You quite obviously have high observing and reasoning skills, if not as high as my brother or I, and so I believe it would not be beneficial in any way to have you give me information on Sherlock."

"I'd have said no to spying anyway."

"Yes. I know. But perhaps you would be better off just helping Sherlock instead of me."

"Mmm, probably," came the reply. But Katherine's mind wasn't on that - it was on Mycroft's previous statement of her observing and reasoning skills to be lower than either of the brothers', which was most likely true, and yet it sort of blew away any of the compliments (or complaints) about her unusually sharp vision. _Whatever_, she thought._ It didn't matter anyway._

"Perhaps you should return to Miss O'Sullivan now, and fulfil your duties."

"Oh, Cindy, yeah," she remembered. "Thanks for showing me how much you care about your little brother."

"I can assure you-"

"And for the ride. Ciao!" Katherine turned and waved to the man behind her. Her footsteps echoed around the warehouse, as she walked back to the black car, but they stopped as soon as Mycroft spoke again.

"Abdomen."

She whipped around.

"What?"

"Where you were shot. Your abdomen." Fists clenched, Katherine nodded, then turned back to the car and slipped in next to 'Prudence'. Despite wanting to just go home and sit with a hot chocolate, she did have responsibilities. Voluntarily.

But as the car drove away, she couldn't help but think about her injury.

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_"Rina, come on. Get out of the way! I don't want to hurt you."_

_"No! Please, just... Don't shoot," she said, tears streaming down her face as she begged._

_"I love you, Rina, but I'm sorry." A loud bang and searing pain. Why had he shot her? There was no reason! _

_"Nate... Oh, Nate. I'm so, so sorry," she tried to explain what she would do, but it happened before she could. The shot threw her hand back and her head slammed on the floor, making her vision spin and turn black. Her last sight was that of another body falling._

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**_Hey, everyone. So, so sorry for the wait, I guess I had a sort of holiday break, but I'll return to regular posting soon; I'm going to pre-write a few chapters to avoid further delays. Sorry! But I hope you liked this chapter - I had to rewrite a few parts because Katherine's sass was OOC. Heh. But please, tell me what you think! Also, if anyone has suggestions for things that happen in the party, I am open to them. Only have one so far._**

**_Thanks to reviewers: shalmarrose, Kitkatlaugh, scarlet tribe, and rycbar15._**

**_Have a lovely week!_**

**_~Lani_**


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